As is well known, an IOL is used to replace the natural lens of the human eye when the natural lens becomes incapable of functioning as desired. A typical IOL includes an optic or lens and one or more fixation members for fixing the IOL in the desired position within the eye.
The optic of an IOL may be constructed of hard, nondeformable materials such as polymethylmethacrylate or of soft, deformable materials such as silicone based or acrylic based materials. One advantage of the deformable IOL's is that they can be deformed into a configuration which permits them to be inserted through a smaller incision into the eye.
In deforming the IOL, the optic is typically folded in a way to cause the IOL to have smaller dimensions which enables it to be inserted through a smaller incision. An IOL which is deformed by forming it into a roll is also folded in the sense that the roll constitutes at least one fold. As used herein, a folded optic, folded IOL and folded condition have reference to an optic which is deformed in any manner, including rolling, that produces a fold.
It is desirable to compactly fold a foldable IOL because this can minimize the length of the incision necessary to insert the folded IOL into the eye. However, because IOL's are very small, they are difficult to grasp and even more difficult to fold into an efficient, compact configuration of minimal dimensions. As an example of size, the optic of a foldable IOL may be in the neighborhood of about 5 to about 7 millimeters in diameter.
Various devices have been proposed for use in inserting a foldable IOL. For example, Bartell U.S. Pat. No. 4,681,102 discloses a hingeably moveable cartridge which effectively facilitates the folding of a foldable IOL for insertion into the eye. In one useful embodiment of such an apparatus, the cartridge includes an elongated injection tube having an open distal end. The elongated injection tube receives the folded IOL from the hingeably movably portion of the cartridge. The IOL is passed out of the open distal end into the eye. Although such an insertion system is generally very effective, further enhancements, for example, in the apparent strength of the insertion system and in the ability of the system to control the release of the IOL into the eye, would be advantageous.